Income Taxes Income Taxes - PacifiCorp - Net Unrecognized Tax Benefits (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Contingency [Line Items]
Unrecognized Tax Benefits	$ 181	$ 128	$ 198
PacifiCorp [Member]
Income Tax Contingency [Line Items]
Unrecognized Tax Benefits	$ 10	$ 12